This invention relates to the use of inter- and intra-molecular ester bridges of the formula EQU --O--(CO)--(CH.sub.2).sub.n --(CO)--
where n=1 to 8, between fatty side chains attached to fat compounds of natural and synthetic origin. These ester bridges suppress caloric availability and modulate the functional characteristics of the fat mimetics.
Dietary fat is the most concentrated source of energy of all the nutrients, supplying 9 kcal/gram, about double that contributed by either carbohydrate or protein. The amount of fat in the American diet has increased in the last 60 years by about 25% (Mead, J., et al. Lipids, Plenum, New York, 1986, page 459), so that fats now provide approximately 40% (or more) of the daily caloric intake. Moreover, technological advances in the food industry, including efficient and safe hydrogenation procedures, have changed the kind of fat in foods.
Because fats are high in calories and because some fats appear to pose a health risk when consumed in large quantities over time, a number of national advisory committees on nutrition have made recommendations differing in detail, but the common theme is a reduction in the total amount of fat in the diet (Gottenbos, J. J., chapter 8 in Beare-Rogers, J., ed., Dietary Fat Requirements in Health and Development, A.O.C.S. 1988, page 109 . Yet fat contributes to the palatability and flavor of food, since most food flavors are fat-soluble, and to the satiety value, since fatty foods remain in the stomach for longer periods of time than do foods containing protein and carbohydrate. Furthermore, fat is a carrier of the fat-soluble vitamins, A, D, E, and K, and the essential fatty acids, which have been shown to be important in growth and in the maintenance of many body functions. Hence, major research efforts have focused on ways to produce food substances that provide the same functional and organoleptic properties as fats, but not the calories.
A number of fat replacements have heretofore been suggested (recently reviewed by Hamm, D. J., 49 J. Food Sci. 419-428 (1984), Haumann, B. J., 63 J. Amer. Oil Chem. Soc. 278-288 (1986) and LaBarge, R. G., 42 Food Tech. 8414 90 (1988)). Hamm divides replacement fats into two broad categories: structurally re-engineered triglycerides modified to retain their conventional functional properties in foods, while removing their susceptibility toward hydrolysis or subsequent absorption during digestion, and materials developed from chemistry unrelated to triglycerides.
Examples of the former class of triglyceride analogues include compounds having the glycerol moiety replaced with alternate polyols (e.g., pentaerythritol in U.S. Pat. No. 2,962,419 to Minich, or sugars, suggested by Hess, K., and Messmer, E., 54B Ber. 499-523 (1921), and patented years later by Mattson and Volpenhein, U.S. Pat. No. 3,600,186, and Meyer, et al., U.S. Pat. No. 4,840,815); compounds having the fatty acids replaced with alternate acids (e.g., branched esters as described in U.S. Pat. No. 3,579,548 to Whyte); compounds having insertions between the glycerol and the fatty acid (e.g., ethoxy or propoxy groups in U.S. Pat. No. 4,861,613 to White and Pollard); compounds having reversed esters (e.g., malonates in U.S. Pat. No. 4,482,927 to Fulcher and trialkoxytricarballylates in U.S. Pat. No. 4,508,746 to Hamm); and compounds having the ester bonds replaced by ether bonds (Can. Pat. No. 1,106,681 to Trost).
Related to triglyceride analogues are dimeric glycerides. Thirty years ago, the U.S.D.A. assessed the caloric availability and digestibility of a series of new-type fats, including dibasic acid-bridged diglycerides (specifically, fumaric, succinic and adipic-bridged diglyceride esters; see Feuge, R. O., and Ward, T. L., 80 J. Amer. Chem. Soc. 6338-6341 (1958); Ward, T. L., et al. 36 J. Amer. Oil Chem. Soc. 667-671 (1959); Feuge, R. O., and Ward, T. L., 37 J. Amer. Oil Chem. Soc. 291-294 (1960); and Shull, R. L., et al. 38 J. Amer. Oil Chem. Soc. 84-86 (1961)). Minich suggested ether-bridged dipentaerythritol esters about the same time (U.S. Pat. No. 2,962,419, column 53 to 76), although he exemplified only monomeric pentaerythritol esters.
Examples of Hamm's second category of fat replacements chemically unrelated to triglycerides are mineral oil (suggested as early as 1894 in U.S. Pat. No. 519,980 to Winter); polyglucose and polymaltose (U.S. Pat. No. 3,876,794 to Rennhard); jojoba wax (W. Ger. Pat. No. 3,529,564 to Anika); polyoxyalkylene esters (U.S. Pat. No. 4,849,242 to Kershner); polyvinyl alcohol esters (U.S. Pat. No. 4,915,974 to D'Amelia and Jacklin) and polysiloxane (Eur. Pat. Ap. Pub. No. 205,273 to Frye).
Nondigestible or nonabsorbable edible fat replacements have proved disappointing when tested in feeding trials, where gastrointestinal side effects occurred, in some cases so extreme that frank anal leakage was observed. Nondigestible fats appear to act as a laxative and are expelled from the body, eliciting foreign body reactions like those early documented for mineral oil (Stryker, W. A., 31 Arch. Path. 670-692 (1941), more recently summarized in Goodman and Gilman's Pharmacological Basis of Therapeutics, 7th ed., Macmillan Pub. Co., N.Y. 1985, pp. 1002-1003). Similarly, experimental fats synthesized by the U.S.D.A group mentioned above exhibited undesirable gastrointestinal side effects when the compounds were fed to rats (Booth, A. N., and Gros, A. T., 40 J. Amer. Oil Chem. Soc. 551-553 (1963)); in several of the balance studies, the diarrhea was so extreme that digestibility coefficients could not be calculated ibid., Table I, p. 552).
Polyglycerol and polyglycerol esters, suggested as fat replacements by Babayan and Lehman (U.S. Pat. No. 3,637,774), have been suggested for use as fecal softening agents as well (U.S. Pat. No. 3,495,010 to Fossel). A number of remedies have been recommended to combat the anal leakage observed when sucrose polyesters are ingested (e.g., employing cocoa butters, U.S. Pat. No. 4,005,195 to Jandacek, incorporating saturated fatty groups, Eur. Pat. Ap. No. 233,856 to Bernhardt, or mixing residues, U.S. Pat. No. 4,797,300 to Jandacek, et al.). Saturated fatty acids have been suggested as anti-anal leakage agents for polyorganosiloxane fat replacements (U.S. Pat. No. 4,925,692 to Ryan), and dietary fiber preparations have been incorporated into foodstuffs containing other fat replacements to help inhibit the diarrheal effect (U.S. Pat. No. 4,304,768 to Staub et al.). Partially digestible fat replacements have also been suggested (U.S. pat. Nos. 4,830,787 and 4,927,659 to Klemann and Finley).